1. Field of the Invention
The present invention relates to a zoom lens system, and more particularly, to a compact zoom lens system having two lens groups for a camera.
2. Description of the Related Art
A compact camera generally requires a compact zoom lens system. A zoom lens system using two lens groups is shown in Japanese Laid-open Patent Publications Nos. Hei 8-29863, Hei 5-11181, Hei 8-76014, Hei 8-50243 and Hei 5-113537, and U.S. Pat. Nos. 5,327,290 and 4,772,106.
Japanese Publication No. Hei 8-29863 uses two lens groups having five lenses, has a zooming ratio of about 1.5, and a focal length of 38-58 mm. This system uses an aspherical lens made of glass material, and has the disadvantage of a slow lens (an overly large minimum f- number) U.S. Pat. No. 4,772,106 has a zooming ratio lower than 1.5.
Japanese Publication No. Hei 5-11181 has a zooming ratio of about 1.54 and uses glass lenses. Japanese Publication Nos. Hei 8-76014, Hei 8-50243 and Hei 5-113537 and U.S. Pat. No. 5,327,290 use more than two aspherical lenses to obtain a zooming ratio of about 2, making manufacturing costs higher.